AC power plugs and sockets

AC power plugs and sockets

AC power plugs and sockets allow electric equipment to be connected to the primary alternating current (AC) power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape, size, and connector type. Different systems of plugs and sockets have been standardized, and different standards are used in different parts of the world.

15 Types in use today

There are currently 15 types of electrical outlet plugs in use today, each of which has been assigned a letter by the US Department of Commerce International Trade Administration (ITA), starting with A and moving through the alphabet. These letters are completely arbitrary: they don’t actually mandate anything.

Type A

Type A plugs are mainly used in the USA, Canada, Mexico & Japan (for a full list, see here for list of standards by country)

Features:

2 pins

not grounded

15 A

almost always 100 – 127 V

socket compatible with plug type A

Type B

Type B plugs are mainly used in the USA, Canada, Mexico & Japan (for a full list, see here for list of standards by country)

Features:

3 pins

grounded

15 A

almost always 100 – 127 V

socket compatible with plug types A & B

Type C

Type C plugs are commonly used in Europe, South America & Asia (for a full list, see here for list of standards by country)

Features:

2 pins

not grounded

2.5 A

almost always 220 – 240 V

socket compatible with plug type C

Type D

Type D plugs are mainly used in India (for a full list, see here for list of standards by country)

Features:

Earthing (grounding)

Note that not all standards have the 3rd Earth pin: electrical safety must be taken into account during installation.

A third contact for a connection to earth is intended to protect against insulation failure of the connected device. Some early unearthed plug and socket types were revised to include an earthing pin or phased out in favour of earthed types.

Different types of plug are used for different IEC appliance classes. The assigned class depends on whether the device is earthed and the degree of insulation it incorporates. Class I, for example, refers to earthed equipment that requires a third contact in the plug and socket, while Class II refers to unearthed equipment protected by double insulation.

List of countries and mains voltage, frequency and plug types

Note: List is provided for information only and believed to be correct at time of publication. Regional variations and changes may occur. Please check locally to be sure.